Hacked Firmware is Not widely available for Wireless hardware.
Almost all of Wireless hardware firmware is propriety, which means that the code is not available and it might be a Bridge of copyright to Hack it.
Happen to be that the line of 802.11g of Linksys, Buffalo Tech, and Belkin are using similar chipsets and the firmware is written in Linux.
Since it is Linux it suppose to be open Code, the Linksys codes was available and thus the proliferation of many variation of the 3rd party firmware. There are some reports that one of firmware that was designed for Linksys might work with certain Buffalo and Belkin units, but I do not think it is a real valid option at the moment.
I doubt that you would find any Hacked firmware to any other Wireless Hardware.
:sun: